Elevator systems are fitted with safety systems to ensure their safe operation. These safety systems typically consist of series-connected safety elements. These safety elements can, for example, monitor the status of shaft or car doors. Known systems for safety circuits are electromechanical or bus-based safety circuits. The reliable operation of such bus-based safety circuits is inspected on a regular basis. The design of and test procedures for such bus-based safety circuits are disclosed, for example, in EP 1159218 A1, WO 2010/097404 A1 or WO 2013/020806 A1. From this prior art however, it is not clear whether or to what extent the safety provision is ensured when connecting or disconnecting temporary participants, such as a manual control device for controlling the elevator system during maintenance work or an input device in which configuration settings of the safety system can be made.